Ossicular implants may be used as ossicular replacements for patients whose hearing has been negatively affected due to loss of function of components in the natural ossicular chain (malleus, incus and stapes).
The natural ossicular chain transmits sound waves from an internal surface of the tympanic membrane (eardrum) through the middle ear to the inner ear. When the natural ossicular chain no longer functions properly, surgical intervention may remove one or more of the ossicles (or portions of ossicles) and to replace them with prosthetic implants.
In implanting an ossicular prosthesis, the functional length of the implant is important for the success of the surgery. The proper length of the implant ensures that the implant mates securely with the locations of the middle ear to which it connects.
Implant lengths vary based on patient anatomy. Conventionally, implant length may be derived using sizers of known lengths or adjustable measuring tools. Once an implant length is determined, a one-piece implant of a preset length may be selected. Alternatively, a surgeon may attempt to set an adjustable length implant to the desired length outside of the patient. Conventional devices employ a method of adjusting and setting the implant length where, for example, a male component is adjusted inside a female component by the surgeon via a measuring “block.” An exterior portion of the female component is generally manually crimped to a specific, unchangeable length using a crimping instrument, effectively squeezing the female component around the male component to secure the single and unchangeable length of the implant. The sized implant is then placed inside the patient and mated at each end with the desired locations in the middle ear.
A shortfall in prior art systems described above is that implant length may be difficult to measure accurately using conventional methods. The implant length may also be difficult to replicate when setting the implant outside the patient. The implant length will often not precisely fit the patient in a manner optimally desired by a surgeon.
Conventional methods to address these shortfalls center around differing instruments and techniques to attempt to accurately size, adjust and set implants prior to insertion into the patient. As illustrated above, conventional methods are limited to irreversibly setting a length of an implant once by a method that involves plastically deforming the implant's components such that the set length cannot be reset or adjusted further after crimping. Additionally, setting the length of conventional implants is a less-than-delicate operation. As such, the conventional length setting process is not conducive to, for example, any in situ application.